A slang that used to stand for "Laugh out loud" but now frequently represents slight humor and acknowledgement of what is said. If someone was seriously laughing, instead of lol they would type LMAO or LMFAO! Lol is just another way to bump the conversation.
Someone: omfg, my dad took my car away from me!
someone2: lol... yea now we can't go to wal-mart.